A connecting bearing of this type can be used especially as a cabin bearing for insulation of typical machine vibrations generated in working tools, for instance, in the driver's cabin of a vibration roller used in the compaction of soil and traffic surfaces.
The comfort and the driving dynamics of a vehicle are determined decisively by the calibration of the chassis frame. Besides the chassis frame concept, decisive is also the elastic behavior of the rubber support for the bonding of the chassis components, for example, a driver's compartment or a driver's cabin, with the machine frame. An elastomer, such as, for example, rubber, contributes, due to its low construction space requirement, its high extendibility, as well as its low density, to the mechanical uncoupling of the oscillating elements (for example, driver's cabin, motor) with fixed elements (for example, machine frames, motor frames).
Chassis frame bearings are often bush bearings with bonded inner and outer pipes. During the vulcanization, elastomeric tensile stress develops due to the contraction, which is later relieved through the subsequent calibration process for reducing the outer diameter. These bearings are then inserted by press fitting into the bearing eye of the chassis frame component.
Besides the insulation against the vibrations, these so-called rubber-metal bearings also provide excellent acoustic insulation for heavily vibrating elements. Modern, powerful drive concepts and vehicle structures with reduced weight generate novel and stronger excitation of vibrations, which are decoupled in a targeted manner by means of calibration of the dynamic characteristics of the rubber metal bearings. These bearings are modified according to the different areas of the applications and transmit the elastic and dampening forces of the motor suspensions through different tuned elastomer routes and thus decouple the disturbing vibrations before their transmission into the frame or the body.
The elastomer mixtures are developed in part in view of their use in different types of applications, and the elastomer mixtures are used on the basis of all the relevant polymer types and chemicals.
As a free-from-play, elastic and vibration-damping connection between the frame and the driver's cab, the driver's cabin bearings contribute significantly towards optimization of the driving dynamics, driving comfort and preservation of coordination by the driver. In order to prevent the interfering vibrations and the noises in the driver's cab, comfort providing suspensions, which offer highest degree of acoustic insulation, have been developed and used. Rubber-metal elements can be used as freely shaped, compact elements, such as, simple cylindrical rubber blocks, for instance, for insulation of vibrations or as aggregate or connected elements.
In case of aggregated springs, it must be ensured, through adequate pressing in the active areas, that the tension on the elastomer is transmitted uniformly as far as possible and without obstruction of the deformation.
In general, the connecting bearings contain two fastening devices, whereby the fastening devices are coupled mechanically through an elastomer, which is constructed as an insulation against vibration. A frequently used type of connecting bearing is a so-called bushing spring (also called silentbloc), in which two bushings with different diameters are connected by means of vulcanized elastomer. The outer bushing is thereby adapted to fit in a bearing box, for example in a frame, and through the inner bushing, which is built significantly longer than the outer bushing and projects over the inner bushing at both ends, a screw for connecting a heavily vibrating element with the frame is inserted. The vibrations acting on the inner bushing are thus dampened by the radially arranged elastomer and are transmitted only with attenuation to the outer bushing, and thus onto the frame.
Disadvantageous in this connecting bearing is that, it must always be mounted in a box, and hence its constructive flexibility is restricted. Disadvantageous is also that the connecting bearing is not well suited for absorbing mechanical excitations vertical to the longitudinal axis. Disadvantageous is also that in case of a swiveling of the fastened element, it abuts slightly upon the outer bushing or the receiver element for the outer bushing (frame), due to which the mechanical decoupling does not take place, and the vibrations are transmitted forth unhampered. Further, due to the impacts, destruction of the elements and/or frame takes place.
In order to provide more space for the play between the frame and the motor, use of a rubber pad is known, which contains two discs and an elastomer vulcanized between the discs. The first and the second disc each are thereby connected by means of a fastening device, for example a screw, with the frame and the motor. Motor vibrations are thereby dampened by the elastomer arranged between the discs.
Disadvantageous in this is that under mechanical excitations that occur vertically with respect to the longitudinal axis, and in particular, under tensile stress, at least one disc can get loosened from the elastomer. In order to remedy for this disadvantage, design of the respective ends of the rubber pad with threaded rods is known, in which one end of the threaded rod is connected firmly by means of the corresponding fastening device with the elastomer (for example, through vulcanization). Disadvantageous in this is that the free construction space for the insertion of the rubber pad is restricted due to the threaded rods. Further, this rubber pad can be built in with difficulty and is thus time consuming, because both the ends of the threaded rods must be tightened by means of nuts on the motor and the frame. Further, due to the elaborate vulcanization process for the bonding of the threaded rods, fabrication of the rubber pads proves to be costly.
Sectional view of the connecting bearings of this kind is shown by way of illustration in FIGS. 3a and 3b. 
FIG. 3a shows a bushing spring H, mounted in a frame R, through which a screw S for fastening the motor M is inserted and fastened. Vibrations, which proceed from the motor M, are thus transmitted forth onto the screw S, where they are dampened by the elastomer E between the inner bushing and the outer bushing and are transmitted further only with attenuation onto the frame. Disadvantageous in this is that the motor M can hit the frame R even due to a swivel within a small angular region, which can lead to damages.
FIG. 3b shows a rubber padding G, known in the state-of-the-art, which can also be resorted to as a connecting element between the motor M and the frame R, whereby the vibrations of the motor M are dampened by the elastomer E contained in the rubber pad and are thus transmitted, with attenuation, onto the frame R. At the respective ends of the rubber pad G, the plates T1, T2 are mounted, on which the respective threaded rods are attached. With these threaded rods are connected on the other hand the frame R and the motor M respectively. Since the plates can easily get loosened from the rubber pad under tensile stress, the threaded rods are fastened by means of fastening devices (not shown) into the elastomer. Disadvantageous thereby is that, due to the special design of the threaded rods, the possible room for the montage is restricted. Besides that, the montage is difficult and time consuming.